Method for configuring wireless local area network in wireless metropolitan area network and wireless communication system supporting the same

ABSTRACT

A method for configuring a Wireless Local Area Network (WLAN) within a Wireless Metropolitan Area Network (WMAN) and a wireless communication system supporting the same are provided. A dual-mode terminal is used as a relay for relaying between the WMAN and the WLAN and the relay divides a total service period into a WMAN period and a WLAN period. For the WMAN period, the relay accesses the WMAN and implements a WMAN service and for the WLAN period, it accesses the WLAN and implements a WLAN service.

CROSS REFERENCE TO RELATED APPLICATION(S)

This application is a Continuation of U.S. application Ser. No.11/655,755, filed Jan. 19, 2007, which claims the benefit under 35U.S.C. §119(a) of Korean Patent Application No. 10-2006-0005875, filedon Jan. 19, 2006 in the Korean Intellectual Property Office, the entiredisclosures of which are incorporated herein by reference for allpurposes.

BACKGROUND

1. Field

The present invention relates generally to a method for configuring aWireless Local Area Network (WLAN) in a wireless communication networkand a wireless communication system supporting the same. Moreparticularly, the present invention relates to a method for configuringa WLAN in a Wireless Metropolitan Area Network (WMAN) and a wirelesscommunication system supporting the same.

2. Description of the Related Art

Mobile communication technology is currently being developed to providemultimedia service by maximizing data rate and frequency use efficiency.A primary example of such technology is a mobile access network. Themobile access network is a generic name for a network that provideshigh-speed wireless services to terminals within specific servicecoverage.

Mobile access networks are separated into Wireless Personal Area Network(WPAN), WLAN, and WMAN according to the sizes of their service coverageareas.

A WLAN is configured with an Access Point (AP) installed at an end pointof a wired network or with a plurality of terminals. The WLAN offershigh-speed wireless communications to terminals within its servicecoverage. The WLAN offers data rate up to 11 Mbps and ensures limitedlow-speed mobility. It works around hotspots such as those available inhouseholds, schools, hotels and conference centers.

Despite its narrow service coverage as compared to the WMAN, the WLANboasts of a wide bandwidth.

It is expected that the development of the mobile access networks willgradually increase dependency on wireless communications. In addition,the proliferation of terminals capable of accessing the mobile accessnetworks such as laptops, Personal Computers (PCs), Personal DigitalAssistants (PDAs), driven by their small size, light weight and lowprice, has increased demands for multimedia services in a mobileenvironment, particularly in hotspot zones.

Despite the widespread use of WLAN terminals, the WLAN covers only alimited area. Accordingly, there exists a pressing need for increasingWLAN coverage.

SUMMARY

An object of the present invention is to address at least the problemsand/or disadvantages and to provide at least the advantages describedbelow. Accordingly, an aspect of the present invention is to provide amethod for configuring a WLAN within a WMAN by use of a relay and awireless communication system supporting the same.

An object of the present invention is to provide a method forconfiguring a WLAN with a neighbor terminal within a WMAN by a dual-modeterminal and a wireless communication system supporting the same.

An object of the present invention is to provide a method for connectinga WMAN to a WLAN configured within the WMAN by a dual-mode terminal anda wireless communication system supporting the same.

An object of the present invention is to provide a method for connectinga terminal located in a WLAN configured within a WMAN to the WMANthrough a dual-mode terminal and a wireless communication systemsupporting the same.

An object of the present invention is to provide a method fordifferentially providing a real-time service and a non-real-time servicein a relay that relays between a WMAN and a WLAN and a wirelesscommunication system supporting the same.

In accordance with the present invention, there is provided a method forconfiguring a WLAN within a WMAN, in which a relay for relaying betweenthe WMAN and the WLAN implements a WLAN service with at least oneterminal connected to the WLAN for a first period and implements a WMANservice with a BS of the WMAN for a second period. Here, the first andsecond periods do not overlap in time.

In accordance with the present invention, there is provided a wirelesscommunication system for configuring a WLAN within a WMAN, in which a BSsupports a WMAN service in the WMAN, at least one terminal receives aWLAN service within the WLAN, and a relay for relaying data between theBS and the at least one terminal implements a WLAN service with at leastone terminal connected to the WLAN for a first period and implements aWMAN service with a BS of the WMAN for a second period. Here, the firstand second periods do not overlap in time.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of certainexemplary embodiments of the present invention will be more apparentfrom the following detailed description taken in conjunction with theaccompanying drawings, in which:

FIG. 1 illustrates the configuration of a wireless communication networkaccording to the present invention;

FIG. 2 illustrates a signal flow for providing a non-real-time servicein the wireless communication network according to the presentinvention;

FIG. 3 illustrates a control operation for providing the non-real-timeservice in a relay according to the present invention;

FIG. 4 illustrates a signal flow for providing a real-time service inthe wireless communication network according to the present invention;

FIG. 5 illustrates a control operation for providing the real-timeservice in the relay according to the present invention;

FIG. 6 illustrates the structure of a beacon frame according to thepresent invention;

FIG. 7 illustrates the structure of a probe request frame according tothe present invention; and

FIG. 8 illustrates the structure of a probe response frame according tothe present invention.

DETAILED DESCRIPTION

The matters defined in the description such as a detailed constructionand elements are provided to assist in a comprehensive understanding ofthe preferred embodiments of the invention. Accordingly, those ofordinary skill in the art will recognize that various changes andmodifications of the embodiments described herein can be made withoutdeparting from the scope and spirit of the invention. Throughout thedrawings, the same drawing reference numerals will be understood torefer to the same elements, features and structures. Descriptions ofwell-known functions and constructions are omitted herein for the sakeof clarity and conciseness.

Terms used herein are defined as follows.

Wireless Metropolitan Area Network (WMAN): a wireless network havingwide service coverage, such as a cellular network, a wirelessbroadcasting network and a WMAN.

Wireless Local Area Network (WLAN): a wireless network deployed andreleased at a particular time in a narrow area such as a conferenceroom. An independent Basic Service Set (IBSS) is one type of WLANtopology. In the present invention, a WLAN can be configured within aWMAN and connected to the WMAN by a relay.

WMAN service: wireless service provided in the WMAN. WMAN services are,for example, a specific contents service and a wireless broadcastingservice.

WLAN service: wireless service provided in the WLAN.

WMAN mode: an operation state in which the WMAN service is provided.

WLAN mode: an operation state in which the WLAN service is provided.

WMAN period (or second period): a period for which the relay accessesthe WMAN and operates in the WMAN mode.

WLAN period (or first period): a period for which the relay accesses theWLAN and operates in the WLAN mode to provide the WLAN service to aterminal within the WLAN.

Relay: a device that provides a connection between the WMAN and the WLANusing radio resources allocated from the networks. For example, adual-mode terminal serves as a relay.

Real-time data: streaming data requesting real-time processing withoutdelay. The real-time data are, for example, voice data and broadcastingdata.

Non-real-time data: data tolerant of transmission delay, such as packetdata.

The following description of the present invention is divided into adescription of the configuration of a wireless communication networkaccording to the present invention and a description of preferredembodiments for providing a WMAN service and a WLAN service over thewireless communication network. Particularly, the present inventionprovides a wireless communication network where a WLAN is configuredwithin a WMAN and a method for efficiently relaying data between theWMAN and the WLAN in the wireless communication network.

FIG. 1 illustrates the configuration of a wireless communication networkaccording to the present invention, in which a WLAN is configured withina WMAN.

Referring to FIG. 1, a Base Station (BS) 112 provides the WMAN serviceto at least one terminal within a WMAN service area 110, which servicecovers a wide area. For example, the WMAN service is a wireless serviceprovided in a cellular network, a wireless broadcasting network, or aWMAN.

A dual-mode terminal 122 supports WLAN service as well as WMAN service.Hence, the dual-mode terminal 122 supports the WMAN service in aprocedure agreed on with the BS 112, operating in WMAN mode. Thedual-mode terminal 122 supports the WLAN service in a procedure agreedon with at least one of WLAN terminals 124, 126 and 128, operating inWLAN mode.

As described above, the dual-mode terminal 122 serves as a relay thatrelays between the BS 112 and the WLAN terminals 124, 126 and 128. Thus,the dual-mode terminal 122 sends data received from the WLAN terminals124, 126 and 128 to the BS 112 and vice versa.

The dual-mode terminal 122 sends and receives data to and from the WLANterminals 124, 126 and 128 by polling them during a WLAN period, inwhich the dual-mode terminal 122 sends and receives data to and from theBS 112.

The dual-mode terminal 122 is capable of simultaneously supporting theWMAN service and the WLAN service, though increasing both throughput andpower consumption. Accordingly, there is a need for minimizing the powerconsumption of the dual-mode terminal 122, while maximizing throughputon a radio link.

For this purpose, the dual-mode terminal 122 alternates between the WMANservice and the WLAN service. A first period and a second period aredefined on the time axis to provide the WLAN service and the WMANservice, respectively. Radio resources can also be allocated separatelyfor the first and second periods.

The dual-mode terminal 122 operates in the WMAN mode for the secondperiod and in the WLAN mode for the first period. The first and secondperiods are determined according to the types and amounts oftransmission data, which will be described later in detail.

The WLAN terminals 124, 126 and 128 are located within a WLAN servicearea 120 and are to receive the WLAN service. A distance over which thedual-mode terminal 122 can provide the WLAN service defines the WLANservice area 120. For example, the WLAN service is a wireless service asprovided in Institute of Electrical and Electronics Engineers (IEEE)802.11 WLAN.

In the wireless communication network with the above-describedconfiguration, the WLAN terminals 124, 126 and 128 can receive the WMANservice via the dual-mode terminal 122.

Provisioning of the WMAN service to WLAN terminals via the dual-modeterminal will be described below in detail in accordance with preferredembodiments of the present invention.

The preferred embodiments of the present invention are described in thecontext of differentiated data, i.e. data requesting real-timetransmission (real-time data) and data requesting non-real-timetransmission (non-real-time data). Yet, the real-time data coexist withthe non-real-time data in a real wireless communication network and thusit is to be clearly understood that differentiated operations for thereal-time data and the non-real-time data may occur together.

A. Transmission of Non-Real-Time Data

A detailed description will be made of a method for sendingnon-real-time data with reference to FIGS. 2 and 3 illustrating a signalflow and a flowchart for providing the non-real-time service.

Referring to FIG. 2, the relay broadcasts information for configuringthe WLAN in a management frame in step 210. The information includes anIDentifier (ID) of the WLAN and a Traffic Indication MAP (TIM). Themanagement frame can be a beacon frame. FIG. 6 illustrates a preferredbeacon frame.

The WLAN ID is a Basic Service Set (BSS) ID (BSS_ID) or an IndependentBasic Service Set (IBSS) ID (IBSS_ID). The BSS_ID is for a WLAN with anAP, and the IBSS_ID is for a WLAN composed of terminals. In the presentinvention, the WLAN ID is the IBSS_ID, by way of example.

The TIM includes information about the amounts of data to be sent tospecific terminals and IDs of the terminals. Therefore, a terminal canestimate the amount of data to receive from the relay based on the TIM.

In step 212, the terminal requests association with the WLAN to therelay by a management frame. The management frame includes the IBSS_IDset in the beacon frame and supported data rates. A probe request framecan be used as the management frame. The probe request frame isgenerally used to discover the service area of the WLAN. FIG. 7illustrates a preferred probe request frame. As illustrated in FIG. 7,the probe request frame includes the IBSS_ID.

The relay determines whether the terminal can associate with the WLAN,considering the capacity of the relay. The relay sends a managementframe based on the determination result in step 214. The managementframe can be a probe response frame. FIG. 8 illustrates a preferredprobe response frame. As illustrated in FIG. 8, the probe response frameincludes the IBSS_ID.

While not shown in FIG. 2, association and authentication mayadditionally be performed between the terminal and the relay.

Upon completion of the terminal's association with the WLAN, the relayindividually allows the terminal to access the WLAN by a control framein step 216. To do so, the relay queries the terminal about whether ithas transmission data. The control frame can be a polling frame based onthe TIM set in from the beacon frame. The TIM includes the IDs ofspecific terminals, thus allowing only the terminals to access the WLAN.

The terminal, which has received the polling frame, exchanges data withthe relay exchange data in data frames in step 218. That is, theterminal constructs a data frame with uplink data and sends it to therelay. The relay also constructs a data frame with stored downlink dataand sends it to the terminal.

When the data transmission is completed, the relay commands the terminalto transition to a dormant state in step 220 in order to prevent theterminal not only from being unnecessarily kept awake for a WMAN periodin which the relay operates in the WMAN mode but also from sending datathat the relay cannot receive. The transitioning to the dormant statecan be commanded by setting a setting value, for example, a NetworkAllocation Vector (NAV) of a frame, to a predetermined value.

Upon receipt of the transition command, the terminal transitions to thedormant state until the next poling. The dormant state is an operationmode that minimizes power consumption.

The above description has been made in the context of a single terminal.In case of a plurality of terminals, steps 216 and 218 are repeated foreach of the terminals. If the transition command should be provided tothe individual terminals, steps 216, 218 and 220 are repeated.

The period for which the relay provides the WLAN service to at least oneterminal within the WLAN is a WLAN period or a first period.

When the WLAN mode operation is completed, the relay transitions to theWMAN mode for providing the WMAN service in conjunction with the BSwithin the WMAN.

In step 222, the relay requests allocation of downlink and uplinkbandwidths to the BS. The relay dynamically determines uplink resourcesbased on the amount of data received from the terminal by the WLANservice. The resulting optimization of uplink resource allocation in theWMAN leads to efficient use of radio resources.

The BS polls the relay by a DownLink MAP (DL_MAP) and an UpLink MAP(UL_MAP) in step 224. The DL_MAP includes downlink information about theallocated downlink resources and the UL_MAP includes uplink informationabout the allocated uplink resources. The BS allocates the downlinkresources according to the amount of buffered data waiting to be sent tothe relay. The BS allocates the uplink resources upon request of therelay.

In step 226, the relay sends the uplink data to the BS according to theUL_MAP and the BS sends the downlink data to the relay according to theDL_MAP.

While one WLAN period and one WMAN period are shown in FIG. 2, theyalternate until the WLAN is released. In other words, the relayalternately implements the WLAN and the WMAN services.

Referring to FIG. 3, the relay sends a beacon frame in step 310. As thebeacon frame includes a WLAN ID (IBSS_ID), a TIM and addressinformation, a terminal that has received the beacon frame can requestaccess to the WLAN.

In step 312, the relay continuously monitors reception of a proberequest frame from the terminal. The monitoring can be about proberequest frames from a plurality of unspecified terminals that areexpected to listen for the beacon frame. The probe request frameincludes the IBSS_ID, requesting access to the WLAN.

Upon receipt of the probe request frame, the relay determines whetherthe terminal can be accommodated, i.e. whether the WLAN service isavailable to the terminal. If the terminal can be accommodated, therelay sends a probe response frame to the terminal in step 314.

In step 316, the relay creates a polling list listing terminals toreceive the WLAN service in a polling order.

The relay selects a target terminal from the polling list and sends apolling frame to the target terminal based on the TIM in step 318. Thepolling frame entitles the target terminal to access the WLAN and tosend data. In step 320, the relay exchanges data with the targetterminal. Upon completion of the data transmission and reception withthe target terminal, the relay determines whether the WLAN service hasbeen completely provided in step 322. The determination involvesdetermining whether the relay has polled all terminals listed in thepolling list.

If the WLAN service is to be further provided, the relay selects thenext target terminal from the polling list in step 318 and exchangesdata with the target terminal in step 320.

However, if the WLAN service has been completed, the relay commands allof the terminals listed on the polling list to transition to the dormantstate by sending, for example, a broadcasting frame with a NAV set to apredetermined value in step 324. Therefore, the terminals are kept inthe dormant state until the next beacon frame or polling frame isreceived. The transitioning to the dormant state prevents the terminalsfrom sending data while the relay operates in the WMAN mode. The dormantstate is an operation mode that minimizes power consumption of theterminals.

The relay calculates the amount of required uplink resources accordingto the amount of data received from the terminals in the WLAN service instep 326. That is, the relay calculates the amount of uplink resourcesto request to the BS according to the amount of buffered data waiting tobe sent to the BS, which in effect minimizes waste of radio resources.

The relay requests allocation of the calculated uplink resources andallocation of downlink resources to the BS in step 328 and is allocatedthe uplink and downlink resources in step 330. The resource allocationis made by a DL_MAP and a UL_MAP sent from the BS in a pollingprocedure.

In step 332, the relay sends data to the BS by the allocated uplinkresources. Specifically, the relay sends the data received from theterminals in the WLAN service to the BS. The relay receives datadestined for the terminals from the BS using the allocated downlinkresources.

When the data transmission and reception with the BS is completed, therelay determines whether the WLAN has been released in step 334. If theWLAN still exists, the relay repeats steps 310 to 324 in the WLAN mode.However, if the WLAN has been released, this implies that the relay doesnot need to support the WLAN service any longer. Thus the relaydiscontinues the WLAN mode operation and performs only the WMAN modeoperation.

B. Transmission of Real-Time Data

A detailed description will be made of a method for sending real-timedata with reference to FIGS. 4 and 5 illustrating a signal flow and aflowchart for providing the real-time service.

Referring to FIG. 4, the relay broadcasts information for configuringthe WLAN in a management frame in step 410. The information includes theIBSS_ID of the WLAN and a TIM. The management frame can be a beaconframe.

In step 412, a terminal sends a probe request frame including theIBSS_ID and information indicating a service type. The service typeinformation identifies a real-time service or a non-real time service.

The relay determines whether the terminal has requested the real-timeservice and also determines whether the terminal can associate with theWLAN, considering the capacity of the relay. When the terminal hasrequested the real-time service, the relay determines a polling periodfor the real-time service (a first polling period) according to thetraffic characteristics of the requested real-time service including theperformance of a Compression/DECompression (CODEC) in the relay, theamount of data to be sent, and the amount of resources to be allocated.For example, if the CODEC performs well, the amount of transmission datais small, or many resources are to be allocated, the first pollingperiod is long.

The relay sends a probe response frame including the determinationresult to the terminal in step 414. The probe response frame includesthe IBSS_ID. It may further include the determined first polling period.

In step 416, the relay requests periodic polling to the BS, offering apolling period (a second polling period).

To do so, the relay determines the second polling period on aterminal-by-terminal basis or commonly for all terminals requesting thereal-time service. In the former case, the periodic polling of the BS isperformed for individual terminals. In the latter case, the periodicpolling is performed for all the terminals requesting the real-timeservice together.

The second polling period is determined, considering trafficcharacteristics including the CODEC performance of the relay, the amountof data for the real-time service, the amount of resources to beallocated and the number of the terminals requesting the real-timeservice.

When the first polling period initially comes, the relay sends a pollingsignal allowing access to the WLAN to a target terminal in step 418. Thepolling signal is generated based on the TIM.

The target terminal and the relay exchange data in data frames in step420. That is, the target terminal sends real-time uplink data to therelay and the relay sends stored real-time downlink data to the targetterminal.

When the data transmission/reception is completed, the relay commandsthe terminal to transition to a dormant state in step 422. For thereal-time data, step 422 is optional. In the next first polling period,the relay exchanges real-time data with the target terminal in steps428, 430 and 432.

As described above, the relay predetermines the first polling period,upon request of the terminal for the real-time service and periodicallyprovides real-time data communications in every first polling period.While the above description has been made in the context of a singleterminal, in case of a plurality of terminals, steps 418 to 432 areperformed for the individual terminals.

The relay receives a first polling signal from the BS in the secondpolling period in step 424. Upon receipt of the polling signal from theBS, the relay transitions to the WMAN mode. The relay receives aDownLink MAP (DL_MAP) and an UpLink MAP (UL_MAP) in the polling signal.The DL_MAP provides information required for receiving downlinkreal-time data, and the UL_MAP provides information required for sendinguplink real-time data.

The relay sends the real-time uplink data to the BS according to theUL_MAP and the BS sends the real-time downlink data to the relayaccording to the DL_MAP in step 426. In steps 434 and 436, the relayperiodically sends and receives real-time data in every second pollingperiod.

If terminals are polled one by one for the real-time service, thereal-time data transmission is also carried out on aterminal-by-terminal basis. However, if only one terminal has requestedthe real-time service or the real-time service is providedsimultaneously to all terminals requesting the real-time data service,the operation is performed for one polling period.

In FIG. 4, only the real-time service is considered. If the real-timeservice and the non-real-time service are considered together, the relayoperates in the WLAN mode in every first polling period.

To be more specific, even when the relay operates in the WMAN mode forthe non-real-time service, it transitions to the WLAN mode in the firstpolling period to provide the real-time service. Upon completion of thereal-time service, the relay resumes the WMAN mode operation for thenon-real-time service.

Also, even when the relay operates in the WLAN mode for the non-realtime data service, upon receipt of a polling signal from the BS, therelay transitions to the WMAN mode and provides the real-time service.Upon completion of the real-time service, the relay resumes the WLANmode operation for the non-real-time service.

While not described above in detail, the first polling period for thereal-time service in the WLAN mode can be equal to the second pollingperiod for the real-time service in the WMAN mode. Also, the first andsecond polling periods may be different.

In the real-time service, the amount of periodically transmittedreal-time data will be constant. Therefore, radio resources may not beallocated periodically for the real-time service. Rather, once radioresources are allocated, they continuously serve the real-time service.In this context, the BS does not need to send a DL_MAP and a UL_MAP eachtime it sends a polling signal. That is, the BS sends the DL_MAP and theUL_MAP only at the first polling for the real-time service and theDL_MAP and the UL_MAP remain in effect thereafter.

Referring to FIG. 5, the relay sends a beacon frame in step 510. As thebeacon frame includes a WLAN ID (IBSS_ID), a TIM, and addressinformation, a terminal that has received the beacon frame can requestaccess to the WLAN.

In step 512, the relay continuously monitors reception of a proberequest frame from the terminal. The monitoring can be about a pluralityof unspecified terminals that are expected to listen for the beaconframe. The probe request frame includes the IBSS_ID, requesting accessto the WLAN.

Upon receipt of the probe request frame, the relay determines whetherthe terminal requests a real-time service in step 514. If the terminalrequests a real-time service, the relay determines whether the real-timeservice is available to the terminal. If the terminal can receive thereal-time service, the relay determines first and second polling periodsfor the real-time service in step 516 and sends a probe response frameto the terminal in step 518.

Steps 512 to 518 are for a single terminal. In the case of a pluralityof terminals requesting the real-time service, the relay determines thefirst polling period and sends the probe response frame on aterminal-by-terminal basis. It is preferred that the relay determinesthe second polling period after detecting all terminals requesting thereal-time service among the terminals within the WLAN. However, if theterminal does request the real-time service, the relay provides anon-real-time service in the procedure illustrated in FIG. 3.

In step 520, the relay requests periodic polling for the real-timeservice to the BS, and simultaneously provides the determined secondpolling period to the BS.

The relay determines whether it is time to poll according to the firstpolling period in step 522. If it is, the relay ends a polling signalfor the real-time service to a target terminal in step 524 and exchangesreal-time data with the target terminal in step 526. If it is not timeto poll in step 522, then the procedure goes to step 528.

The relay determines whether a polling signal has been received from theBS in step 528. Reception of the polling signal implies that it is timefor the BS to poll according to the second polling period. The pollingsignal includes a UL-MAP and a DL-MAP for the real-time service.

Upon receipt of the polling signal from the BS, the relay sends andreceives data to and from the BS according to the UL_MAP and the DL_MAPin step 530.

If it is not time to poll according to the first polling period and thepolling signal has not been received from the BS, the relay continuesthe non-real-time service in step 532.

Upon completion of the data transmission/reception to and from thetarget terminal or the BS, the relay determines whether the targetterminal has requested release of the real-time service in step 534. Ifthe real-time service is to be provided further, the relay returns tostep 522. If the real-time service has been released, the relay ends thereal-time service. Then, the relay operates only for the non-real-timeservice.

While the real-time service and the non-real-time service have beendescribed separately in the preferred embodiments of the presentinvention, it is obvious to those skilled in the art that the relay canimplement the real-time service and the non-real-time service in asingle algorithm. That is, when a polling period comes for the real-timeservice during the ongoing non-real-time service, the relay discontinuesthe non-real-time service and provides the real-time service. When thereal-time service is completed, the relay resumes the non-real-timeservice.

As is apparent from the above description, the present inventionadvantageously configures a WLAN temporarily by use of a dual-modeterminal supporting the WMAN service and the WLAN service. When a WMANis commercialized, the WLAN can be extended using the dual-modeterminal. Therefore, network configuration cost is saved and packetusers can be considerably increased.

As the dual-mode terminal supports the WMAN service and the WLAN servicein time division, the throughput of a radio link is maximized and thepower consumption of the dual-mode terminal is minimized.

While the invention has been shown and described with reference tocertain preferred embodiments of the present invention, it will beunderstood by those skilled in the art that various changes in form anddetails may be made therein without departing from the spirit and scopeof the present invention as defined by the appended claims and theirequivalents.

The invention claimed is:
 1. A method for relaying data by a dual-modeterminal in a wireless communication system, the method comprising:performing a first communication with at least one terminal for a firstperiod, to transmit data received from a base station (BS) to the atleast one terminal or to receive data from the at least one terminal;and performing a second communication with the BS for a second period,to transmit data received from the at least one terminal to the BS or toreceive data for the at least one terminal from the BS, wherein thefirst period and the second period are determined based on amounts andtypes of data to be transmitted in each of the first period and thesecond period, and wherein the dual-mode terminal alternates between thefirst period and the second period a plurality of times until datatransmission and reception of the at least one terminal related to theBS is finished.
 2. The method of claim 1, wherein uplink resources forthe second communication are determined based on an amount of datareceived from the at least one terminal during the first communication,and an allocation request for the determined uplink resources istransmitted to the BS.
 3. The method of claim 2, wherein the performingthe first communication comprises: broadcasting a beacon frame includingidentification information of a network for the first communication tothe at least one terminal; sequentially allowing the first communicationto the at least one terminal requesting the first communication;transmitting and receiving data to and from the requesting at least oneterminal; and commanding the requesting at least one terminal totransition to a dormant state, when the data transmission and receptionare completed.
 4. The method of claim 1, wherein the performing thefirst communication comprises: broadcasting a beacon frame includingidentification information of a network for the first communication tothe at least one terminal; sequentially allowing the first communicationto the at least one terminal requesting the first communication;transmitting and receiving data to and from the requesting at least oneterminal; and commanding the requesting at least one terminal totransition to a dormant state, when the data transmission and receptionare completed.
 5. The method of claim 1, wherein a network for the firstcommunication is different from a network for performing the secondcommunication, the network for the first communication is included inthe network for performing the second communication.
 6. The method ofclaim 1, wherein data transmitted and received in the firstcommunication and the second communication are non-real-time data. 7.The method of claim 6, further comprising, when the at least oneterminal requests a real-time service, periodically transmitting andreceiving by the dual-mode terminal real-time data between the at leastone other terminal and the BS.
 8. The method of claim 7, wherein thereal-time data transmission and reception comprises: determining a firstpolling period for the real-time service-requesting at least oneterminal; determining a second polling period when no more otherterminals request the real-time service; notifying the BS of thedetermined second polling period; transmitting and receiving real-timedata to and from the real-time service-requesting at least one terminalby periodically polling the real-time service-requesting at least oneterminal according to the first polling period; and transmitting andreceiving the real-time data to and from the BS by periodic pollingbased on the second polling period.
 9. The method of claim 8, whereinthe first and second polling periods are determined according to trafficcharacteristics of the real-time service.
 10. The method of claim 9,wherein the real-time data transmission and reception to and from the BScomprises transmitting and receiving the real-time data to and from theBS using predetermined resources.
 11. A wireless communication system,comprising: a base station (BS); at least one terminal; and a dual-modeterminal configured to perform a first communication with to the atleast one terminal for a first period, to transmit data received fromthe BS to the at least one terminal or to receive data from the at leastone terminal, and to perform a second communication with the BS for asecond period, to transmit data received from the at least one terminalto the BS or to receive data for the at least one terminal from the BS,wherein the first period and the second period are determined based onamounts and types of data to be transmitted in each of the first periodand the second period, and wherein the dual-mode terminal alternatesbetween the first period and the second period a plurality of timesuntil data transmission and reception of the at least one terminalrelated to the BS is finished.
 12. The wireless communication system ofclaim 11, wherein the uplink resources for the second communication aredetermined based on an amount of data received from the at least oneterminal during the first communication, and an allocation request forthe determined uplink resources is transmitted to the BS.
 13. Thewireless communication system of claim 12, wherein the dual-modeterminal broadcasts a beacon frame including identification informationof a network for the first communication to the at least one terminal,sequentially allows the first communication to the at least one terminalrequesting the first communication, transmits and receives data to andfrom the requesting at least one terminal, and commands the requestingat least one terminal to transition to a dormant state, when the datatransmission and reception are completed.
 14. The wireless communicationsystem of claim 11, wherein the dual-mode terminal broadcasts a beaconframe including identification information of a network for the firstcommunication to the at least one terminal, sequentially allows thefirst communication to the at least one terminal requesting the firstcommunication, transmits and receives data to and from the requesting atleast one terminal, and commands the requesting at least one terminal totransition to a dormant state, when the data transmission and receptionare completed.
 15. The wireless communication system of claim 11,wherein a network for the first communication is different from anetwork for performing the second communication, the network for thefirst communication is included in the network for performing the secondcommunication.
 16. The wireless communication system of claim 11,wherein data transmitted and received in the first communication and thesecond communication are non-real-time data.
 17. The wirelesscommunication system of claim 16, wherein, when the at least oneterminal requests a real-time service, periodically transmitting andreceiving by the dual-mode terminal real-time data between the at leastone terminal and the BS.
 18. The wireless communication system of claim17, wherein the dual-mode terminal determines a first polling period forthe real-time service-requesting at least one terminal, determines asecond polling period, when no more other terminals request thereal-time service, notifies the BS of the determined second pollingperiod, transmits and receives real-time data to and from the real-timeservice-requesting at least one terminal by periodically polling thereal-time service-requesting at least one other terminal according tothe first polling period, and transmits and receives the real-time datato and from the BS by periodic polling based on the second pollingperiod.
 19. The wireless communication system of claim 18, wherein thefirst and second polling periods are determined according to trafficcharacteristics of the real-time service.
 20. The wireless communicationsystem of claim 19, wherein the relay transmits and receives thereal-time data to and from the BS using predetermined resources.
 21. Adual-mode terminal in a wireless communication system, the dual-modeterminal comprising: a transmitter; a receiver; and a controllerconfigured to perform a first communication with at least one terminalfor a first period, to transmit data received from a base station (BS)to the at least one terminal or to receive data from the at least oneterminal, and to perform a second communication with the BS for a secondperiod, to transmit data received from the at least one terminal to theBS or to receive data for the at least one terminal from the BS, bycontrolling the transmitter and the receiver, wherein the first periodand the second period are determined based on amounts and types of datato be transmitted in each of the first period and the second period, andthe dual-mode terminal alternates between the first period and thesecond period a plurality of times until data transmission and receptionof the at least one terminal related to the BS is finished.
 22. Thedual-mode terminal of claim 21, wherein a network for the firstcommunication is different from a network for performing the secondcommunication, the network for the first communication is included inthe network for performing the second communication.